(a) Field of the Invention
This invention relates to a method of treating waste water and sewage and more particularly, but not by way of limitation, to a method for enhanced removal of putrescible organic matter, such as fecal waste, grease, oil, bacteria and slime, from inorganic grit, such as sand, gravel, concrete particles, and like material found in waste water and sewer water.
(b) Discussion of Prior Art
In the modern remediation of waste water and sewage, a fluid is first screened to remove paper, plastic, rags and the like. Secondarily, the fluid is then treated for removing inorganic grit material from the organic material suspended therein. The de-gritted fluid is then transferred to a tank or a holding pond to allow the organic waste material to settle to a bottom of the tank or the pond. Later, the material is removed as sludge for further processing or taken to a land fill.
Heretofore, there have been a number of systems for removing grit from a sewage flow. For example, a typical grit collector system includes a dewatering device such as an inclined screw conveyor mounted in a tank. This type of device is called a classifier, screw classifier, grit washer, or dewatering conveyor. While modern classifiers are successful in removing much of the putrescible organic material in the waste water and preventing it from going to a landfill, these units are complex in design, expensive and fail to capture smaller inorganic grit particles suspended in the liquid. Therefore, the fine grit remains in the treated waste water and returns to a water treatment plant for further processing, where it plugs up digesters, wears out pumps and water treatment equipment and causes ongoing maintenance and operational problems. The subject method greatly reduces the above mentioned fine grit maintenance problems and with reduced operation costs, while enhancing the capture of fine putrscisble material for return to a treatment plant for further treatment and/or disposal while decreasing the putrescible material going to the landfill.
In U.S. Pat. No. 3,130,157 to Kelsall et al., a hydro-cyclone is disclosed and used for the classification of metallurgical pulps or ore concentrates from a mining operation. The object of the hydro-cyclone is to improve the efficiency of classification by decreasing the proportion of fine particles in the underflow pulp using an increased cyclonic action to wash fine particles from between voids in the large suspended particles. This type of fluid cyclone unit, while widely used in the mining industry, has not been used in conjunction with a method for treating waste water and sewage with the following unique features, objects and advantages as discussed herein.